Process for the production of dyestuff intermediates



United States Patent 2,991,292 PROCESS FOR THE PRODUCTION OF DYESTUFF INTERMEDIA'IES Eberhard Degener and Siegfried Petersen, Leverkusen,

Germany, assignors to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed Mar. 18, 1958, Ser. No. 722,160 Claims priority, application Germany Mar. 18, 1957 6 Claims. (Cl. 260-327) This invention relates to novel dithiacyclohexenes-(l) and to a process for their production.

It is an object of the present invention to provide novel dithiacyclohexenes more particularly 1,2-dicyano-3,6-dithiacyclohexenes-( 1). A further object is to provide a simple process for the production of these cyclohexenes. More objects will appear hereinafter.

These objects are attained in accordance with the present invention by reacting the salts of 1,2-dicyano-1,2-dimercapto-ethylene with organic compounds which contain 2 exchangeable groups in a-position.

The cyclohexenes obtained by the process of the present invention can be substituted in the 4- and/or 5-position for example by cyanoor aryl groups or by alkyl groups which can contain hetero atoms such as 0. Furthermore these cyclohexenes can contain a second double bond between the C-atoms in 4- and S-pcsition.

Salts of the l,Z-dicyano-1,2-dimercapto ethylene are for example the alkali metal salts, the alkaline earth metal salts or the zinc or lead salts.

Compounds having two exchangeable groups in a-position are, for example, 1,2 dichloroethane, 1,2 dibromethane, l,2-dibromo-l phenylethane, ethane-1,2 dimethane-sulphonate, propane 1,2 di-p-toluene-sulphonate or 1,2-dibromo-cyclohexane.

The reaction may be carried out in the presence of inert solvents such as ethanol, acetone, dirnethyl formamide, water methyl glycol acetate, dioxan, pyridine or xylene. It is advantageous to operate in a dilute solution. The reaction is, moreover, preferably carried out at the lowest possible temperatures.

The optimum temperature range depends in each case on the reactivity of the exchangeable groups. In general, satisfactory results are attained by operating at temperatures within the range of between 0 and 160 C., preferably 2080 C., but other temperatures may also be chosen.

The compounds which are obtained by the present invention have a good stability and can be used as intermediate products, for example, for the production of dyestufis.

Example 1 200 grams of the disodium salt of 1,2-dicyano-1,2-dimercaptoethylene are dissolved in 800 millilitres of methanol and nitrogen is passed over. 200 grams of 1,2-dibromethane in 100 millilitres of methanol are added dropwise with stirring and the temperature is kept at 20-25 C. by external cooling with water. Stirring is continued at 25 C. for half hour, the temperature is then slowly raised and the reaction finally completed by boiling under reflux for one hour. Upon cooling with ice, a mixture of sodium bromide and 1,2-dicyano3,G-dithiacyclohexene- (l) is filtered off by suction which is freed from sodium bromide by washing with water. By concentration of the alcoholic reaction solution, further quantities of dinitrile may be precipitated. A total of about 160 grams of the dicyan-dithia-cyclohexene are thus obtained. The crude product is purified by recrystallisation from 70 per- Patented July 4,

cent alcohol, 50 percent acetone or acetic acid using A- suction-filtration and washing with acetone, 6.5 parts by weight of 1-amino-3-imino 4,7-dithia-4,5,6,7 tetrahydroisoindolenine are obtained 4 parts by weight of l-amino-3-imino-4,7-dithia-4,5,6,7- tetrahydroisoindolenine or the tautomeric 1,3-diimino-4,7- dithia-4,5,6,7-tetrahydroisoindolenine and 1 part by weight ofcopper acetate are dissolved in parts by weight of ethylene glycol. A cotton fabric is impregnated with this solution, the excess solution removed by squeezing and the fabric heated in a drying oven to -l40 C. for 10 minutes. After boiling out with soap solution, there remains on the cotton a strong, dull violet dyeing fast to light.

Example 2 18.6 parts by weight of the disodium salt of the 1,2- dicyano-l,2-dimercapto ethylene, 9.9'parts by weight of 1,2-dichloroethane and 100 parts by 'volume of absolute alcohol are heated in a closed vessel for 6 hours to 100 C. The precipitate obtained is filtered oil? and extracted with chloroform. The chloroform extract is introduced into the fourfold amount of water and this mixture then extracted several times with chloroform. The chloroform extracts are washed with water treated with active carbon and dried with sodium sulfate. Upon'evaporating thesolvent 13 parts by weight of 1,2-dicyano-3,6-dithia-cyclo hexene-(l) is obtained which is purified as described in Example 1.

Example 3 Example 4 26.4 grams of 1,2-dibromo-1-phenylethane are added to a suspension of 21 grams of the disodium salt of 1,2- dicyano-1,2-dimercaptoethylene in 150 millilitres of absolute alcohol. The mixture is first stirred at 40 C. for 30 minutes while passing through nitrogen and then heated under reflux for 90 minutes. After cooling, the precipitate formed is filtered off by suction and extracted with chloroform. By evaporation of the chloroform and concentration of the alcoholic reaction solutions, a total of 10.2 grams of 4-pheny l-l,2-dicyano-3,6-dithia-cyclohcxene-(l) are obtained. M.P. 129130 C.

Example 5 To a solution of 20 parts by weight of the disodium salt of l,2-dicyano l,2-dimercapto ethylene in 130 parts by volume of absolute ethanol parts by weight of 2,3-dibrom-1-methoxypropan dissolved in 40 parts by volume of ethanol at 30 C., while stirring and passing through nitrogen. Thereafter the mixture is stirred for 30 minutes at 40 C. and then heated under reflux for 90"minutes. Upon cooling the sodium bromide formed is filtered oif, the solution is concentrated and'thenpoured intowater; The oil obtained is taken up in ether. The ether solution is then washed with water and dried with sodium sulfate. Upon evapo rating the solvent 10 parts by weight of 4-methoxymethyl- 1,Z-dicyano-S,6-dithia-cyclohexene-(1) are obtained as an oil from which yellow crystals are obtained upon cooling.

Example 6 95 grams of the disodium salt of 1,2-dicyano-l,2-dimercaptoethylene and grams of the sodium salt of di-nbutylnapthalene-sulphonic acid are dissolved in 500 millilitres of water; 40 millilitres of ethylene chloride are then added dropwise at 50-60 C. and the mixture is vigorously stirred at ,this temperature for two hours. Upon cooling to 20 .C., suction-filtration of the solid portions, washing with water and drying, the resultant l,2-dicyano-3,6-dithiacyclohexene-(l) is isolated. Yield: 22 grams (M.P. 132-133" C.).

Example 7 297 parts by weight of the disodium salt of 1,2-dicyano- 1,2-dimercapto ethylene are dissolved in a mixture of 300 parts of water and 300 parts by weight of methanol. Thereafter 120 parts by volume of ethylenebromide are added at C. The mixture is stirred for 5 hours at 25 C. Thereafter the precipitate is filtered ofi, washed with 'a50 percent methanol and dried. Thus 130 parts by weight of 1,2-dicyano-3,6-dithia-cyclohexene-(1) are obtained.

Example 8 150 parts by weight of NaS CSCN+3(CH NCHO (obtained by the process described by B'ahr and Schleitzer in Chemische Berichte, vol. 88, page 1771) are dissolved in 200 parts of water. After 20 hours, the precipitated sulfuris filtered on. To the filtrate there are added 22 parts by volume of ethylenebromide and 100 parts by volume of methanol. This mixture is stirred for 7 hours at 20-25 C. Thereafter the precipitate is filtered off, washed with a 50 percent methanol and dried. Thus 31 parts by weight of 1,2-dicyano-3,G-dithiacyclohexene-(1) are obtained.

Instead of the methanol, there can be used also another solvent which is miscible with Water, such as dimethylformamide or dioxane. If the process is carried out in the absence of oxygen, a very pure nearly white product is obtained. If the process is carried out in the presence of oxygen similar pure products can be obtained, if the process is carried out in the presence of an antioxydant such as potassium horanate.

Example 9 Into a solution consisting of 186 parts by weight of the disodium salt of 1,2-dicyano-1,2-dimercapto ethylene, 10 parts by weight of the sodium salt of dibutylnaphthaline sulfonic acid and 1 part by weight of potassiumborhydride dissolved in 1500 parts of water and 750 parts by volume of dimethylformamide, there are added dropwise within minutes 150 parts by weight of 2,3-dichloropropionitrile at 25-50 C. Upon about further 30 minutes the reaction product begins to crystallize. Upon cooling oil the precipitate is filtered 01f, washed with water and dried. Thus 135 parts by weight of the nearly colourless 12,4-tricyano-3,6-dithia-cyclohexene-(1) are obtained. The product can be recrystallized from chlorobenzene. Thepure, colourless product dissolves with yellow colour in concentrated sulfuric acid or diluted aqueous ammonia.

there are added dropwise 23 We claim: 1'."

s l l ON CN s GHQ-( J I H mK IoN H s CHaOCH i ON HK iorr 5. A compound of the formula C-CN X H C-CN wherein X is a radical selected from the group consisting of and CH(CN)CH 6. A process for the production of a compound of the formula v wherein X is a radical selected from the group consisting of and -CH(CN)CH which comprises contacting at a temperature from 0 to C. a salt of l,2-dicyano-l,2- dimercapto ethylene, said salt being selected from the group consisting of alkali metal salts, alkaline earth metal salts, zinc salt and lead salt, with a reactant corresponding to the following structural formula wherein each X is a member selected from the group consisting of chloro and bromo; R is a member selected from the group consisting of hydrogen, methyl, CH OCH phenyl and nitrile; and each A is hydrogen when Y is a single bond connecting the two carbon atoms of the structural formula and are nil when Y is a double bond connecting the two carbon atoms of the structural formula.

References Cited in the file of this patent Richters Organic Chemistry, Elsevier, N.Y., Vol. IV, pages 4-5 (1947).

G. Bahr et a1.: Chemische Berichte 1957), vol. 90,

5 page 43 8-443.

G. Bahr et ah: Chemical Abstracts, 1957, vol. 51, C01. 9587c, an abstract of G. Bahr et aL, Chem. Tech. (Berlin) 1956, vol. 8, pages 597-8. 

5. A COMPOUND OF THE FORMULA
 6. A PROCESS FOR THE PRODUCTION OF A COMPOUND OF THE FORMULA 